Metal via structure

ABSTRACT

A filled metal via having an adhesive layer configured on bottom is disclosed. The adhesive layer enhances bonding force between the filled metal via and a bottom element. Further, stacked metal vias can be made to save spaces to enhance circuit density for an electronic system.

BACKGROUND

Technical Field

The present invention relates to a metal via structure, especially relates to a filled metal via structure which has an adhesive layer lying on bottom. The adhesive layer enhances bonding forces between the metal block and a bottom element.

Description of Related Art

FIG. 1 shows a prior art.

FIG. 1 shows that US2012/0273960 discloses a semiconductor package. A semiconductor die 124 is embedded in an encapsulant 194. The semiconductor die 124 has a plurality of through silicon via (TSV) 132 within the die 124, and has a plurality of through mold via (TMV) 200 within the encapsulant 194. A top build-up structure 202 and a bottom build-up structure 210 are made for external interconnect for the semiconductor package. The top build-up structure 202 has a redistribution circuitry 204, the bottom build-up structures 210 has a redistribution circuitry 212. A plurality of solder balls 216 are configured on a bottom side of the package.

The disadvantage for the prior is that the redistribution circuitry 204 has a first conformal metal via 20A and a second metal via 20B. An offset 22 is needed between the first metal via 20A and 20B in a lateral side. The offset 22 needs more space for circuitry layout and consumes more substrate area. It is a long desire to enhance circuit density higher and higher in the semiconductor device technology. It is noticed that the offset between two metal vias not only wastes substrate used but also reduces circuit density.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a prior art.

FIGS. 2A-2J show a fabrication process embodiment according to the present invention.

FIG. 3 shows a modified embodiment according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A filled metal via having an adhesive layer configured on bottom is disclosed. The adhesive layer enhances bonding force between the filled metal via and a bottom element. Further, stacked metal vias can be made to not only save spaces but also enhance circuit density for an electronic device. A shorter circuit not only enhances signal intensity but also lessens signal transmission time.

The adhesive layer according to the present invention has a thickness roughly of 0.3 um and can be made as thick as 1 um depending on design choices. The metal circuit according to the present invention can be one of Gold (Au), Silver (Ag), Copper (Cu), Aluminum (Al) or equivalents. The adhesive layer according to the present invention can be one of Titanium (Ti), Chromium (Cr), Niobium (Nb), Tungsten (W), and Titanium Tungsten (TiW).

FIGS. 2A-2J show a fabrication process embodiment according to the present invention.

FIG. 2A shows: preparing a substrate 30 with at least a metal pad 301 configured thereon; a first dielectric layer D1 is configured on a top surface of the substrate 30; the first dielectric layer D1 has a first opening 302 and the metal pad 301 has a top surface exposed from the opening 302 of the first dielectric layer D1. The metal pad 301 as shown in the figure is an example only, which can be replaced by a metal circuit or a metal pillar such as a through silicon via (TSV), through glass via (TGA), or a through mold via (TMV) . . . etc.

FIG. 2B shows: applying a patterned first photoresist PR1 on a top surface of the first dielectric layer D1, the first photoresist PR1 has a second opening 303 aligned with the first opening 302;

FIG. 2C shows: performing a first metal evaporation to form a first adhesive layer 304, the first adhesive layer 304 is conformably distributed on a wall surface of the first opening 302 and on a top surface of the exposed area of the metal pad 301;

FIG. 2D shows: performing a second metal evaporation to form a first metal block 305 on a top surface of the first adhesive layer 304;

FIG. 2E shows: stripping the first photoresist PR1;

FIG. 2F shows: flattening the first metal block 305 so that the first metal block 305 has a top surface coplanar with a top surface of the first dielectric layer D1;

FIG. 2G shows: applying a patterned second photoresist PR2, the second photoresist PR2 has a third opening 306 which covers at least a top surface of the first metal block 305;

FIG. 2H shows: performing a third metal evaporation to form a second adhesive layer 307 on a top surface of the first dielectric layer D1; the second adhesive layer 307 covers at least a top surface of the first metal block 305;

FIG. 2I shows: performing a fourth metal evaporation to form a first metal circuit 307 on a top surface of the second adhesive layer 307;

FIG. 2J shows: stripping the second photoresist PR2.

FIG. 3 shows a modified embodiment according to the present invention.

A second metal via structure can be made and stacked on a top surface of the first metal via through a similar fabrication process.

FIG. 3 shows: forming a second dielectric layer D2 on a top surface of the first metal circuit 308; the second dielectric layer D2 has an opening 404A aligned with the first metal block 305; the opening 404A exposes an area of the first metal circuit 308;

forming a third adhesive layer 404 to cover at least a top surface of the exposed area 404 of the first metal circuit 308;

forming a second metal block 405 on a top surface of the third adhesive layer so that the second metal block 405 is aligned with the first metal block 305; wherein the second metal block 405 has a top surface coplanar with a top surface of the second dielectric layer D2;

forming a fourth adhesive layer 407 on a top surface of the second dielectric layer D2; the fourth adhesive layer 407 has a first end extended to cover a top surface of the second metal block 405; and

forming a second metal circuit 408 on a top surface of the fourth adhesive layer 407.

While several embodiments have been described by way of example, it will be apparent to those skilled in the art that various modifications may be configured without departs from the spirit of the present invention. Such modifications are all within the scope of the present invention, as defined by the appended claims.

Numerical system  30 substrate 301 metal pad 302 first opening 303 second opening 304 first adhesive layer 305 first metal block 306 third opening 307 second adhesive layer 308 first metal circuit 404 third adhesive layer 404A opening 405 second metal block 407 fourth adhesive layer 408 second metal circuit D1 first dielectric layer D2 second dielectric layer PR1 first photoresist PR2 second photoresist 

What is claimed is:
 1. A metal via structure, comprising: a bottom metal, having a top surface exposed from a first dielectric layer; a first adhesive layer, configured on a top surface of the bottom metal; and a first metal block, configured on a top surface of the adhesive layer; having a top surface coplanar with a top surface of the first dielectric layer.
 2. A metal via structure as claimed in claim 1, further comprising: a second adhesive layer, configured on the top surface of the first dielectric layer; having a first end extended to cover a top surface of the first metal block; and a first metal circuit, configured on a top surface of the second adhesive layer.
 3. A metal via structure as claimed in claim 1, wherein the first adhesive layer extends to wrap side surfaces of the first metal block so that the metal block does not contact with the first dielectric layer directly.
 4. A metal via structure as claimed in claim 1, wherein the first metal block is a conductive material selected from a group consisting of Au, Ag, Cu and Al.
 5. A metal via structure as claimed in claim 1, wherein the first adhesive layer is a conductive material selected from a group consisting of Ti, Cr, Nb, W, and TiW.
 6. A metal via structure as claimed in claim 1, wherein the first adhesive layer has a thickness less than 1 um.
 7. A metal via structure as claimed in claim 6, wherein the first adhesive layer has a thickness roughly of 0.3 um.
 8. A metal via structure as claimed in claim 1, wherein the bottom metal is selected from a group consisting of a metal pad, metal circuit, through silicon via, through glass via, and through mold via.
 9. A metal via structure as claimed in claim 2, wherein the first metal circuit is a conductive material selected from a group consisting of Au, Ag, Cu and Al.
 10. A metal via structure as claimed in claim 2, wherein the second adhesive layer is a conductive material selected from a group consisting of Ti, Cr, Nb, W, and TiW.
 11. A metal via structure as claimed in claim 2, further comprising: a second dielectric layer, configured on a top surface of the first metal circuit; a top surface of an area of the first metal circuit aligned with the first metal block, exposed from the second dielectric layer; a third adhesive layer, configured on the top surface of the exposed area of the first metal circuit; and a second metal block, configured on a top surface of the third adhesive layer, having a top surface coplanar with a top surface of the second dielectric layer.
 12. A metal via structure as claimed in claim 11, wherein the third adhesive layer extends to wrap side surfaces of the second metal block.
 13. A metal via structure as claimed in claim 11, wherein the second metal block is a conductive material selected from a group consisting of Au, Ag, Cu and Al.
 14. A metal via structure as claimed in claim 11, wherein the third adhesive layer is a conductive material selected from a group consisting of Ti, Cr, Nb, W, and TiW.
 15. A metal via structure as claimed in claim 11, wherein the third adhesive layer has a thickness less than 1 um.
 16. A metal via structure as claimed in claim 15, wherein the first adhesive layer has a thickness roughly of 0.3 um.
 17. A metal via structure as claimed in claim 11, further comprising: a fourth adhesive layer, configured on a top surface of the second dielectric layer; having an end extended to cover a top surface of the second metal block; and a second metal circuit, configured on a top surface of the fourth adhesive layer.
 18. A fabrication process for making a metal via structure, comprising: preparing a substrate with at least a metal pad configured thereon; a first dielectric layer configured on a top surface of the substrate; the first dielectric layer has a first opening and the metal pad has a top surface exposed from the opening of the first dielectric layer; applying a patterned first photoresist PR1 on a top surface of the first dielectric layer D1, the first photoresist PR1 has a second opening aligned with the first opening; performing a first metal evaporation to form a first adhesive layer, the first adhesive layer is conformably distributed on a wall surface of the first opening and on a top surface of the exposed area of the metal pad; performing a second metal evaporation to form a first metal block on a top surface of the first adhesive layer; stripping the first photoresist PR1; and flattening the first metal block so that the first metal block has a top surface coplanar with a top surface of the first dielectric layer.
 19. A fabrication process for making a metal via structure as claimed in claim 18, further comprising: applying a patterned second photoresist PR2, the second photoresist PR2 has a third opening which covers at least a top surface of the first metal block; performing a third metal evaporation to form a second adhesive layer on a top surface of the first dielectric layer; the second adhesive layer covers at least a top surface of the first metal block; performing a fourth metal evaporation to form a first metal circuit on a top surface of the second adhesive layer.
 20. A fabrication process for making a metal via structure as claimed in claim 19, further comprising: forming a second dielectric layer on a top surface of the first metal circuit; the second dielectric layer has an opening aligned with the first metal block; the opening exposes an area of the first metal circuit forming a third adhesive layer to cover at least a top surface of the exposed area of the first metal circuit; forming a second metal block on a top surface of the third adhesive layer so that the second metal block is aligned with the first metal block; wherein the second metal block has a top surface coplanar with a top surface of the second dielectric layer; forming a fourth adhesive layer on a top surface of the second dielectric layer; the fourth adhesive layer has a first end extended to cover a top surface of the second metal block; and forming a second metal circuit on a top surface of the fourth adhesive layer. 